The present invention relates to track chain tensioning devices and pertains particularly to an automatic track chain adjusting system.
The under carriage and endless track of track-type vehicles is normally subjected to fairly rapid wear because of the harsh environment in which such vehicles normally operate. It has been found that proper adjustment or tension in the track of such vehicles can enhance the life of the track assembly as well as the performance of the vehicle. This constant wear of the track chain results in undue slack in the track chain which further increases the rate of wear of the track assembly.
The maintenance of proper tension in such track assemblies is difficult under field conditions and normally requires experienced maintenance personnel with proper tools.
Track chain wear is also rapidly increased whenever the tension is also improperly increased. Dirt and mud which occasionally accumulate on the track will quickly increase the tension of a properly adjusted, clean chain assembly. A properly adjusted track appears "too loose" to most operators who frequently over-tighten the track for this reason. This also results in increased wear of the track.
Another problem encountered with these track-type vehicles is the occasional passage of relatively large unbreakable foreign objects such as rocks and the like between the track chain and the drive sprocket or idler. Such passage of objects can result in the breakage of the chain or other elements of the system if the recoil mechanism of the system cannot accommodate the object.
These forces and the passage of large objects between the track and idler are accommodated by means of large recoil mechanisms using large coil springs. Numerous proposals have been made to overcome one or more of these problems with the prior art. These proposals include hydromechanical recoil and adjusting system which are disclosed, for example, in the following patents: U.S. Pat. No. 3,647,270, issued Mar. 7, 1972 to Althaus; U.S. Pat. No. 3,733,107, issued May 15, 1973 to Cote et al; and, U.S. Pat. No. 3,901,563, issued Aug. 26, 1975 to Day.